1. Field of the Invention
This invention relates to compositions for the treatment of textile materials, to processes for their application, and to the products of such processes. The object of the textile treatment is to improve certain textile properties, and in particular the dimensional stability of textile articles, especially those which contain wool or other animal hairs.
2. Description of the Prior Art
It is well known in the art that many textile fabrics exhibit poor dimensional stability. For example, laundering causes severe shrinkage of textiles composed of wool or other animal hairs. This technical disadvantage seriously restricts the applications of wool in the consumer market and much research has been undertaken in order to modify the surface of the natural fibres in order to provide them with resistance to shrinking. The most useful of the processes currently being advocated involves the use of costly polymeric compositions of limited commercial availability. Where these compositions are capable of being cured (cross-linked) under relatively mild conditions, it is found that their storage stability is poor due to premature cross-linking. Still other treatments involve complex multistage processes, impart an undesirable harshness to the material, or damage the fibres and reduce wearing properties.
Emulsions of vinyl copolymers which are crosslinkable offer an attractive method of treating textiles since they are inexpensive to manufacture, confer a soft handle, and are stable to heat, light and drycleaning. Accordingly, a large variety of such polymers have become available commercially, the majority of which are crosslinkable via N-methylol groups and an acid catalyst (see H. Warson, The Applications of Synthetic Resin Emulsions, Ernest Benn Ltd., London, 1972). Unfortunately, copolymers of this type show very poor washfastness on certain textile materials, especially those containing wool or other keratinous fibres and therefore cannot impart shrinkresistance to these materials at low application levels (i.e. less than about 4% on weight of material). Oxirane containing vinyl copolymers are rarely used in textile treatments at the present time since they have hitherto failed to provide a significant improvement in properties over the somewhat cheaper N-methylol containing counterparts. Oxirane groups, however, can be readily introduced into vinyl copolymers by copolymerization of glycidyl-containing monomers for example.
Glycidyl-containing copolymers are disclosed in U.S. Pat. No. 2,606,810 for the treatment of wool-containing textiles. It is found in practice, however, that the very high treatment levels of 7% or more which are necessary to impart shrinkresistance to prolonged laundering results in an unacceptable impairment to the handle. This is particularly evident in highly succeptible fabrics such as fine worsteds. Similar considerations apply to the oxirane containing copolymers disclosed in British Pat. No. 935,018 (Copolymers of cyclic epoxyalkyl methacrylates) or in U.S. Pat. No. 3,678,098 (copolymers of amino substituted acrylates which have been alkylated with an epihalohydrin). Morover, it is found that no substantial improvement is gained by employing conventional acidic or basic catalysts or additional crosslinking agents such as the aminoplast resins or epoxy resins, the use of which is well known in the art (see H. Mark, N. S. Wooding and S. M. Atlas, "Chemical Aftertreatment of Textiles", Wiley, N.Y., 1971).
The use of a variety of polyamines is also known in the prior art. U.S. Pat. No. 2,925,317 discloses a shrinkresist treatment for wool involving various polyalkylenimines. However, in practice it is found that at application levels which achieve only moderate shrinkresistance, the fabrics are conferred with an unacceptable harshness and an intolerable degree of yellowing after curing, presumably due to the high level of amino nitrogen which is present and which becomes subject to oxidation under these conditions.
These problems are not overcome when the compositions also contain epoxy resins as disclosed in U.S. Pat. No. 2,817,602 since the moderate level of shrinkresistance which is achieved is only possible when the polyalkylenimine represents more than two thirds of the applied solids. Alternative polymeric polyamines are disclosed in U.S. Pat. No. 2,781,335 as the reaction product of solution polymerized glycidyl-containing copolymers and monoamines, but in practice, adequate shrink resistance is not obtained at low application levels. Similarly, the limited shrinkresist effectiveness of the water soluble reaction products of isocyanate prepolymers and polyamine hydrochlorides in compositions containing a polyacrylate has been described recently by B. O. Bateup and B. E. Fleischfresser (Textile Research Journal Vol. 48, 417 (1978)).
Additional compositions from which one obtains in practice only a limited degree of shrinkresistance are disclosed in Australian Pat. No. 474,471 in which blends of an anionic polymer and a polymeric cationic compound (e.g. polyethylenimine of molecular weight above 2,000) are employed, preferably in the presence of a crosslinking agent and mercapto compounds. Amongst the group of suitable anionic polymers are mentioned polyacrylates containing a wide variety of reactive groups; the patentees indicating a preference only for the carboxyl group. In examples 1, 2, 3, 4, 5, 6 and 8 thereof, commercial polyacrylates of unknown composition are employed.
A further disadvantage which limits the utility of the abovementioned prior art processes is that techniques for their exhaustion onto textile materials from a long liquor have not been developed. This is a method of application which is particularly suited to knitted garments and garment pieces.